DE69722761T2 - Initial position sensor - Google Patents

Description

Territory of invention

The present invention relates generally relates to optical scanning devices and in particular on position detection devices for optical scanning devices.

background

Imaging devices such as z. B. optical scanning devices are known in the art and generate machine readable image data signals that are representative for a scanned object, such as B. a page of printed text. The image data signals can then digitized and / or saved for later use become. The image data signals can z. B. used by a personal computer to take an image the scanned object on a suitable display device, such as B. a cathode ray tube, to create. Alternatively, you can the image data is printed on a printer.

A typical imaging device (e.g., an optical scanner) includes an illuminator and a optical system to illuminate the object and a small one Region of the illuminated object, which is usually referred to as a "scan line", to the surface to focus a light sensitive detector in the scanner is positioned. Image data representing the entire object, can then by traversing the illuminated scan line across the entire object, either by moving the object relative to the Illumination and the optical arrangement or by moving the lighting and the optical arrangement with respect to the Property. The lighting system can be a suitable one White light source (e.g., a fluorescent or incandescent lamp) to include the To illuminate the object, whereas the optical system is a lens arrangement may include the image of the scan line on the illuminated surface to focus the detector.

The photosensitive detector array may have a charge coupled device (CCD), though other devices can also be used. A typical CCD can a big number individual cells or "pixels", where each an electric charge in response to one Exposure collects or builds up. Because the size of the accumulated electrical charge in a particular cell or pixel on the intensity and duration Depending on the exposure, a CCD can be used to get bright and dark spots on an image focused on it capture. In a typical scanner application the charge built up in each of the CCD cells or pixels, measured and then at regular intervals, known as sampling intervals, discharge for a typical Scanning device can be about 5 milliseconds or similar, though other sampling intervals can be used.

The term "image light" as used herein refers focus on the light that passes through the lens assembly onto the surface of the Detector arrays is focused. Depending on the type of scanner can be the image light from the document or object being scanned will be reflected, or it may be transmitted through the object or document become. The image light is essentially divided into three steps converted digital signals. First, every pixel converts to the detector the light it receives into an electrical charge around. Second, the charges from the pixels through an analog amplifier Analog voltages converted. Finally, the analog voltages digitized by the analog-digital (A / D) converter. This digital Signals can then as desired processed and / or saved.

Optical scanners and various components thereof are described in U.S. Patent Nos. 4,926,041 OPTICAL SCANNER of David Wayne Boyd; 4,709,144 COLOR IMAGER UTILIZING NOVEL TRICHROMATIC BEAM SPLITTER AND PHOTOSENSOR from Kent J. Vincent; 4,870,268 COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS by Kent J. Vincent and Hans D. Neuman; 5,038,028 OPTICAL SCANNER APERTURE AND LIGHT SOURCE ASSEMBLY by Boyd u. a. and 5,227,620 APPARATUS FOR ASSEMBLING COMPONENTS OF COLOR OPTICAL SCANNERS by Elder u. a. each of which is hereby specifically disclosed by reference for everything their revelations have been incorporated.

Regardless of the configuration a particular scanner, e.g. B. whether the same color or is a monochrome (i.e., gray scale) scanner, the most such scanners very accurately locate the physical Know the scan window. Most scanners typically do this by locating a reference mark on the scanner housing, the very precise regarding of the physical scan window is placed. Once the reference mark is located, the scanner knows the exact location of the physical scanning window and is ready to scan objects or documents.

Most scanners use a sensor, often referred to as an "output sensor", to sense the location of the moving carriage when the scanner is initially turned on. Generally speaking, the output sensor has a simple switch, which can be optical or electromechanical, the ge may be closed when the car is at or near its rearmost position, and open if it is not. Then, when the output sensor switch is closed, when the scanner is initially turned on (ie, powered up), the scanner moves the carriage forward until it detects a reference mark positioned at a certain known location with respect to the home position. This means that when the carriage is located approximately in the home position, the scanner roughly knows how far to move the carriage to detect the reference mark. On the other hand, if the output sensor is open when the scanner is initially turned on, the scanner will move the carriage backward until it detects the reference mark. In either case, once the reference mark is located, the scanner "knows" the exact location of the physical scan window and is ready to scan objects or documents. In summary, the output sensor is used to obtain a "rough" location of the cart while the Reference mark is used to get a more precise location.

European patent application number 0 441 535 A2 discloses a method and an apparatus for electronic Determine the physical position of essential scanner elements in terms of a document reference corner before scanning a document. The disclosed device comprises a carriage, a detector, the plurality has light-sensitive elements for detecting objects in a field of view, with each photosensitive element producing an output signal, that is related to the incident light, at least one of the photosensitive elements is an image capture element and at least one of the photosensitive elements is a position detection element is a reference mark, which is marked on the housing of the device, and an output sensor for detecting the starting position. Also disclosed is a method for moving the cart under the device Use the output sensor in the home position. The reference mark is used to position the scan window at the beginning of a To determine scanning operation.

U.S. Patent Number 5,115,478 discloses a scanner suitable for an image reader which can accurately grasp the top of a document region on which a document is placed.

While the previous arrangement is effective to make it the scanner to allow to determine the location of the physical scan window and the carriage moving to the beginning of the window makes them use an additional Switch required. In addition to increasing the cost and complexity of the scanner elevated the use of an additional switch Moreover the length of the "tolerance stack". This means that there the output sensor switch is not always accurate with respect to the reference mark is arranged, the output sensor switch sufficiently far behind the reference mark must be placed so that the reference mark is always captured even in the case can be in which the partial tolerances stack up very disadvantageously. Because the partial tolerance stacking is housed in a worst case must become, the result can be an increase the total scanner length his.

Therefore there is a need for one improved method and device for moving the carriage of an imaging device upon startup in a known starting position. That is, to determine the location of the physical scan window.

Summary the invention

There is one device and one Method for moving a movable carriage which is housed in a housing Imaging device is attached to a home position according to claim 1 and 8, respectively.

Short description of the drawings

Illustrative and currently preferred embodiments of the invention are in the accompanying Drawings shown:

1 Fig. 4 is a top view of an optical pickup using an initial position sensor according to the invention, showing the position of the reference mark on the inner surface of the top panel and the movable carriage assembly;

2 Figure 12 is a side elevation of the optical pickup device 1 a portion of the side panel being removed to show the position of the movable carriage assembly;

3 Fig. 4 is a pictorial elevation of the movable carriage assembly showing the optical system for focusing an image of the scan line on the detector assembly;

4 Fig. 4 is a top view of a detector array showing the position sensing elements and the image sensing elements;

5 Fig. 4 is a top view of a document being scanned by an image forming device illustrating the movement of the scan line across the document;

6 FIG. 10 is a block diagram of the optical pickup of FIG 1 and 2 at a high level; and

7 10 is a flow diagram of a method for determining a starting position in accordance with the present invention.

detailed Description of the invention

An initial position sensor according to the present invention is shown in FIG 1 shown how it could be used to determine the starting position of a movable carriage assembly 18 an imaging device and an optical pickup to detect or determine when initially turned on. As soon as the starting position is determined, the carriage arrangement 18 moved to a home position as needed and the scanner 11 is ready for use.

The initial position sensor uses a section of the same detector array or a CCD 62 ( 4 ) which is used to generate the image data representative of the object being scanned. In particular, the detector array 62 positioned so that a small section 19 its pixel the presence or absence of a reference mark 15 can grasp that on an inner surface 23 an upper board 14 the scanner is positioned. In other words, the small section defines 19 of the detector array 62 a field of view 29 , depending on the position of the carriage arrangement 18 the reference mark 15 includes. The little section 19 of the detector array 62 is referred to herein as the "position detection section" or "position detection pixels" of the detector array 62 designated. The neighboring pixels 21 of the detector 62 define a field of view 42 ( 5 ) consistent with an illuminated scan line and are referred to herein as the "image capture section" or the "image capture pixels".

If the scanner 11 An electronic control and image data processing system monitors at the beginning 46 ( 6 ) the position detection pixels 19 detector array 62 to determine whether the reference mark 15 within the field of view 29 the position detection pixel 19 is. If the reference mark 15 within the field of view 29 of the position detection section 19 of the detector array 62 the control system knows 46 that the car 18 is positioned in or near the home position. On the other hand, the control system knows when the reference mark 15 not within the field of vision 29 the position detection pixel 19 is that the car 18 is in a different position. In both cases, the electronic control and image data processing system operates 46 the carriage actuator 20 ( 6 ) then as needed to the carriage arrangement 18 to move into the appropriate position until the control system 46 a transition 25 between the reference mark 25 and the inner surface 23 the top panel 14 detected. The car 18 is then placed in the home position and the scanner 11 is ready to get a document 12 scan.

An advantage of the present invention is that they eliminates the need for a separate output sensor or switch arrangement to provide to the starting position of the movable carriage assembly to determine.

Having briefly described the initial position sensor according to the present invention and some of its more essential features and advantages, the initial position sensor will now be described in detail. Referring to the 1 to 4 the initial position sensor is shown as it is in any of a wide range of image sensing devices or scanning devices 11 that are known in the art could be incorporated to generate machine-readable image data representative of an image of an object 12 , such as B. a sheet of paper on which graphics are provided, as in 5 is shown.

The imaging system or scanner 11 can produce monochrome (ie, gray scale) image data or color image data.

In a preferred embodiment, the imaging system or scanner 11 a housing 22 include that an upper panel 14 with an opening or a picture window 27 in the same, which is adapted to a transparent plate 16 take. A moving car 18 that is below the transparent plate 16 is positioned, can move back and forth along a movement axis AA to scan a document 12 that on the plate 16 positioned to achieve. In a preferred embodiment, the carriage is moving 18 in the forward direction (by an arrow 50 displayed) to scan the document. Alternatively, the document could be moved by moving the cart 18 be scanned in the opposite direction.

The window 27 the top panel 14 includes a front end 33 and a rear end 35 , The inside surface 23 the top panel 14 also includes a reference mark 15 (shown in phantom), located at a known position with respect to the image window 27 located. Alternatively, the reference mark can be located at a known position with respect to the scanning axis AA. In a preferred embodiment, the reference mark is 15 at about the back end 35 of the scan window 27 and to one side on the in 1 positioned as shown. The reference mark 15 is positioned so that its rearmost extent 31 extends beyond the rearmost position at which the carriage 18 can be arranged. The foremost extent or transition line 25 the reference mark 15 extends to a known position along the scan axis AA. The reference mark 15 is also positioned so that it is within the scanning field of view 29 the position detection pixel 19 on the detector array 62 is as described in more detail below.

It is preferred that the reference mark tion 15 a different reflectance than the inner surface 23 the top panel 14 so that it is easily passed through the position detection pixels 19 and the control system 46 can be detected. In a preferred embodiment, e.g. B. has the inner surface 23 the top panel 14 is essentially white in color, whereas the reference mark 15 has a substantially black color. However, other colors and / or arrangements can be used without departing from the scope of the invention. If e.g. B. the inner surface 23 the top panel 14 is a dark or black color, the reference mark may be light or white in color. In any case, all that is required is sufficient contrast between the reference mark 15 and the inner surface 23 exists so the two can easily go through the control system 46 can be distinguished.

The reference mark 15 can by any conventional device on the inner surface 23 the top panel 14 be attached. In a preferred embodiment, e.g. B. can be the reference mark 15 have a sticker or label on the inside surface 23 the top panel 14 is attached to the appropriate position. Alternatively, the reference mark on the inner surface 23 be painted.

Referring to 3 can the carriage arrangement 18 a car body 24 which is adapted to a light source assembly 26 and an opening arrangement 28 record, although a slot opening arrangement is not always required. The carriage arrangement 18 also includes the various components of the optical system 30 , The carriage arrangement 18 is slidable on the scanner housing 22 attached so that the same with respect to the transparent plate 16 by a suitable car actuator 20 (in 3 not shown, however in 6 shown) can be moved in a manner known in the art around a continuous scan image of the object 12 on the image capture section 21 of the detector or the CCD array 62 ( 4 ) to create. Generally speaking, the carriage actuator 20 a drive motor (not shown) and a drive belt or cable assembly (also not shown) for moving the carriage assembly back and forth 18 under the plate 16 have along the scan axis AA. However, since many different types of carriage actuators 20 for accomplishing the aforementioned functions are known and available to those skilled in the art, and because of the particular structure of the carriage actuator 20 in achieving the objects of the present invention is not essential, the carriage actuator 20 not described in more detail.

The optical system 30 that is inside the carriage assembly 18 attached, a plurality of mirrors 32 . 34 and 36 have that within the housing 24 are attached to a folded light path 56 to define the distance from the illuminated scan line 42 of the object 12 ( 5 ) through the opening 28 and the lens assembly 38 and on the detector arrangement 44 extends. The optical system 30 also focuses light through the inner surface 23 and / or the reference mark 15 is reflected on the detector arrangement 44 ,

It is noted that the particular configurations of the carriage and optical arrangement 18 and 30 are not essential in achieving the objects of the invention and any of a wide range of configurations could be used for such arrangements without departing from the scope of the invention. Therefore the car and the optical arrangement 18 and 30 shown and described herein are considered to be illustrative and generally generic for such arrangements. However, the structure of the carriage and the optical arrangement can serve as an example 18 and 30 be similar or identical to those described in Boyd et al. U.S. Patent 4,926,041, which is specifically incorporated herein by reference for all of his disclosures.

In a preferred embodiment, the detector arrangement 44 a light sensitive detector 62 (e.g. a CCD) having a linear array of detector elements or pixels 17 having. According to the present invention, the detector is 62 regarding the optical arrangement 30 positioned so that a small section 19 the pixel 17 a field of view 29 that defines the reference mark 15 includes. This little section of pixels 19 is referred to herein as a "position detection section" or "position detection pixel". The remaining section 21 of the detector elements or pixels 17 defines a field of view that is the illuminated scan line 42 ( 5 ) includes. Consequently, this remaining section 21 referred to herein as "image capture section" or "image capture pixels".

While the number of pixels or elements 17 that the position detection section 19 has, is not particularly essential, the position detection section 19 have a sufficient number of pixels to reliably indicate the presence or absence of the reference mark 15 within the field of view 29 to deliver. Consequently, the position detection section 19 in a preferred embodiment, about sixteen (16) individual detector elements or pixels 17 although more or fewer pixels could be used as well.

Referring to the 1 and 5 can the scanning device 11 act to an image or document 12 ( 5 ) on the transparent plate 16 ( 1 ) is positioned by moving the carriage 18 about the document in the forward or scan 50 scan. The direction of a movement opposite to the arrow 50 is referred to herein as the "reverse" or "reverse" direction. As a result, the field of vision runs 42 through the image capture section 21 of the detector 62 is defined in the scanning direction 50 through the picture. In a preferred embodiment, the carriage is moving 18 in the forward direction 50 from the back end 35 to the front end 33 of the window 27 ( 1 ) or scans the same way, although it could easily scan in the opposite or reverse direction.

It is also noted that, while the scanning device shown and described herein, scanning by moving the light source and optical assemblies 26 and 30 (ie carriage arrangement 18 ) regarding the object 12 achieved, the same a scanning by moving the object 12 with respect to a fixed lighting and optical arrangement, as will be apparent to those skilled in the art. Such an alternative embodiment would include a fixed light source and optical assembly (not shown) and a moveable plate (not shown) to move the object being scanned with respect to the fixed light source and optical assembly.

The electronic control and image data processing system 46 captures image data from the image capture pixels 21 of the detector 62 and processes the captured image data to place it in a form suitable for subsequent processing by the host computer 48 is. It also monitors the position detection pixels 19 of detector 62 to determine whether the reference mark 15 within the field of view 29 is. Now referring to 6 can the electronic control and image data processing system 46 an analog amplifier 55 include that with the detector array 44 via a suitable line 61 connected is. The analog amplifier 55 receives a serial stream of charges from the CCD array 62 ( 4 ) that the detector system 44 ( 3 ), and subsequently converts each charge into an analog voltage. The analog-digital (A / D) converter 57 receives the analog voltages from the amplifier 55 over a line 63 and digitized them. In a preferred embodiment, A / D converter 57 generates a 12-bit digital word that represents the varying intensity of each pixel.

A secondary control 58 controls the timing of the CCD array 62 ( 4 ) and the A / D converter 57 via respective control lines 65 and 67 , The auxiliary control 58 receives the digitized data from the A / D converter 57 via a bus 69 , provides all necessary formatting and image processing and stores the digitized data via a bus 71 in a RAM 68 , The auxiliary control also manages 58 the transfer of data from the RAM 68 to the host computer 48 via a host interface 53 , The host computer 48 can be an image processing system or a general purpose computer. A main control 66 is provided to initiate an image scanning operation and the slave control 58 over a bus 73 to set up and monitor. The main control 66 also controls the carriage actuator 20 ,

In a preferred embodiment, the slave controller includes 58 an image processor 59 , a format processor 78 , a state control 94 and direct memory access (DMA) control 96 , State control 94 provides a clock and other control signals to the operation of the CCD array 62 and the A / D converter 57 via respective control lines 65 and 67 to synchronize. The DMA control 96 controls the storage and removal of data from RAM 68 , The DMA control 96 communicates with the RAM 68 over a bus 75 and with the host interface 53 over a bus 77 , The image processor 59 provides image processing skills such as: B. changing the resolution of the digitized image from the A / D converter 57 , The format processor 78 enables the data format of the digitized image to be changed before it is stored in RAM 68 and to the host interface 53 is saved. The format processor 78 can e.g. B. the data representing the digitized image, the RAM 68 present in a 1, 4, 8, 10 or 12 bit per pixel format.

In a preferred embodiment, the secondary control 58 implemented as an ASIC (application specific integrated circuit). The main control 66 can be a universal microprocessor such. B. a Motorola 68HC11, available from Motorola, Inc., Schaumburg, Illinois. The CCD array 62 may include a Toshiba TCD137C available from Toshiba America Electronic Components, Inc., Irvine, California.

The operation of the start position sensor is best in 7 can be seen and is described as follows. On starting the scanner 11 supplies the main control 66 the light source 26 with energy to the inner surface 23 the top panel 14 to illuminate. The image processor 59 then checks the data signals through the pixels in the position detection region 19 of the detector array 62 generated by the detector system 44 having. When bright areas are detected, the main controller knows 66 that the car 18 is at a certain position other than the home position, and operates the carriage actuator 20 to move the carriage 18 to move in the reverse direction, ie opposite to the arrow 50 , The position detection pixels 19 are continually by the image processor 59 monitored until the transition 25 the reference mark 15 is detected (ie until the position detection pixels 19 At this point the main controller 66 would become the carriage actuator 20 apply, moving the cart 18 to stop. The car 18 is now positioned in the starting position and the scanning device 11 is ready to scan documents.

On the other hand, if the position detection pixels 19 the car is dark after an initial start-up 18 positioned in or near the home position. The main control 66 then actuates the carriage actuator 20 to the carriage 18 to move in the forward direction (ie in the direction of the arrow 50 ) until the transition 25 is being captured. The car 18 is now positioned in the starting position and the scanning device 11 is now ready to scan documents.

It should be noted that when designing the car actuator 20 is such that the car 18 may "cross" the transition 25 a substantial distance (particularly if it is moving in the reverse direction to find the reference mark), it may prove necessary or desirable that the main controller 66 the car 18 moved in the forward direction (ie in the direction of the arrow 50 ) until the transition 25 is being captured.

It is contemplated that the concepts of the invention, , which are described herein, are variously embodied otherwise can, whereby it is intended that the appended Expectations conceived to alternative embodiments to encompass the invention, except to the extent that it already exists are limited by the state of the art.

Claims (9)

Device for moving a moving carriage ( 18 ) in a housing ( 22 ) an image forming device ( 11 ) is attached, to a starting position, the device having the following features: a detector ( 62 ) which has a plurality of photosensitive elements ( 17 ) for detecting objects in a field of view, each light-sensitive element ( 17 ) generates an output signal which relates to a light incident thereon, at least one of the light-sensitive elements ( 17 ) an image capture element ( 21 ) and at least one of the photosensitive elements ( 17 ) a position detection element ( 19 ) is; a reference mark ( 15 ) so on the housing ( 22 ) is positioned so that the reference mark ( 15 ) in the field of view ( 29 ) of the position detection element ( 19 ) of the detector ( 62 ) if the car ( 18 ) is located in or near the starting position; an image data processor ( 46 ) with the detector ( 62 ) is connected and responsive to the output signals generated by the same to determine whether the reference mark ( 15 ) in the field of view ( 29 ) of the position detection element ( 19 ) of the detector ( 62 ) is located; and an actuator ( 20 ) that with the moving carriage ( 18 ) is connected and to the image data processor ( 46 ) responds to the moving carriage ( 18 ) in response to whether the reference mark ( 15 ) in the field of view ( 29 ) of the position detection element ( 19 ) of the detector ( 62 ) to move. The device of claim 1, wherein the position sensing element ( 19 ) of the detector ( 62 ) to the image capture element ( 21 ) of the detector ( 62 ) is adjacent. The device according to claim 1 or 2, wherein the position detection element ( 19 ) of the detector ( 62 ) to the image capture element ( 21 ) of the detector ( 62 ) adjoins. The device according to one of claims 1 to 3, wherein the detector ( 62 ) a plurality of position detection elements ( 19 ) which is adjacent to a plurality of image capturing elements ( 21 ) are positioned. The device according to one of claims 1 to 4, wherein the housing ( 22 ) a picture window ( 27 ) and an inner surface ( 23 ) and has an outer surface and in which the reference mark ( 15 ) on the inner surface ( 23 ) of the housing ( 22 ) adjacent to the image window ( 27 ) is positioned. The device according to one of claims 1 to 5, wherein the image data processor ( 46 ) between the image capture element ( 21 ) of the detector ( 62 ) generated output signal and by the position detection element ( 19 ) of the detector ( 62 ) generated output signal differs. The device according to one of claims 1 to 6, wherein the detector ( 62 ) comprises a charge coupled device. A method of moving a carriage ( 18 ) in a housing ( 22 ) an image forming device ( 11 ) is attached, to a starting position, the method comprising the following steps: monitoring a position detection element ( 19 ) on a detector ( 62 ) which has a plurality of photosensitive elements ( 17 ) for detecting objects in a field of view, each light-sensitive element ( 17 ) generates an output signal which relates to a light incident thereon, at least one of the light temp sensitive elements ( 17 ) an image capture element ( 21 ) and at least one of the photosensitive elements ( 17 ) the position detection element ( 19 ) is; Moving the moving carriage ( 18 ) in a first direction towards a known position of a reference mark ( 15 ) if the reference mark ( 15 ) not in the field of view ( 29 ) of the position detection element ( 19 ) is located; Stopping the car ( 18 ) if the reference mark ( 15 ) in the field of view ( 29 ) of the position detection element ( 19 ) is located; and moving the moving carriage ( 18 ) in a direction opposite to the first direction if the reference mark ( 15 ) in the field of view ( 29 ) of the position detection element ( 19 ) of the detector ( 62 ) is located. The method of claim 8, further comprising the step of stopping the movable carriage ( 18 ) from its movement in the opposite direction as soon as the reference mark ( 15 ) out of sight ( 29 ) of the position detection element ( 19 ) is located.